This invention relates to a front loader, such as for example a skid steer loader or a multi-terrain loader, and more particularly to a machine having a pair of forward-extending lift arms that support and position an implement, such as a digging bucket or the like. Loaders of various types are well known in the art, and typically have a body and ground engaging drive elements supporting the body. The drive elements may be either front and rear pairs of driven wheels, or left and right driven endless tracks. Typically, such a loader has left and right interconnected lift arm assemblies that are pivotally mounted to respective tower portions of the body near the rear of the loader. The implement, such as for example a bucket with a forward facing row of teeth, is typically pivotally attached at the forward ends of the lift arms. Hydraulic lift actuators are connected between the body and the lift arm assemblies to raise and lower the lift arms together. One or more hydraulic actuators are also connected between the lift arm assemblies and the implement to tilt the implement relative to the lift arms during operation of the loader.
Loaders of this type have a great many uses, and they typically have a wide variety of implements that can be readily interchanged. Examples of such implements include dirt buckets, utility buckets, multi-purpose buckets, pallet forks, utility grapple buckets, light material buckets, utility forks, industrial grapple buckets, industrial grapple forks, angle blades, augers, brooms, cold planers, hydraulic hammers, landscape rakes, landscape tillers, material handling arms, stump grinders, trenchers, and vibratory compactors. Dirt buckets and other implements may be used for excavating material, and also for grading, both in a forward direction and in a reverse direction by back blading.
Traditional guidance and automated blade control systems of the type used with graders and bulldozers typically include position sensors directly mounted on the machine blades. This is not practical with a loader because a sensor on a loader implement, such as a loader bucket, would likely be damaged quickly due to the way in which loader buckets are used. For example, although positioning a laser receiver directly on a mast that extends upward from a loader implement simplifies the elevation measurement process, since the implement is always a fixed distance below the measured elevation of the laser receiver, the receiver will be subjected to treatment so rough that it will not function for an extended period of time.
Nevertheless, it is highly desirable to be able to determine the position of a loader implement, and to provide for control of the loader implement, either by displaying for the operator the position of the implement with respect to the desired height of the implement, or by automated control of the implement.